Mull is a joy to cycle. Opt for the west coast road and then you avoid all the traffic going up to Tobermory.
After an initial climb around the south of the island, the descent along the western coast is absolutely stunning, with amazing views of the coastline and small islands dotting out to sea.
Once you reach Tobermory in the North you can either travel back down the east coast of the island to complete the circuit in Craignure, or, if you are cycling Mull as part of a larger tour, you can catch the ferry from Tobermory to Kilchoan and carry on up the mainland coastline